How fast would a girl lose interest?

I like a girl
And at some point I think she liked me
For over 3 months She was texting Everyday
And asking to meet me just the two of us

She is my friend , and I was dumb as fuck and I didn’t notice
A month ago, the texts got less and less and now I realised but it is too late

I feel I took too much time to understand
now I really miss our talks and time together

Was she interested and then she lost the interest?
How fast would a girl lose interest?
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